ABSTRACT
The structural design of buildings was based for centuries, and even today for the greater part of the world, on the assumption that loading is not time-dependent, with only some special exceptions where cyclically moving masses cause vibrations. In this respect, for centuries and even today the core of the education of the structural engineer has been based on statics and strength of materials. Therefore, it can be easily understood why the first efforts for quantitative evaluation of the seismic actions on buildings, at the beginning of twentieth century and for many decades since, have been based on a simulation with static loads of the time-dependent inertial forces due to seismic vibrations. Even today, the American Codes of Practice for earthquake-resistant structures (ASCE 7-05) has as reference method of analysis the ‘lateral force method of analysis’, where, of course, many of the consequences of dynamic behaviour of structures have been incorporated.
